Ka 4 Rhönlerche II Kollision mit Kabel nahe Pilatussüdfuss, Schweiz

Am 2. Juli 1967 kollidierte eine Alexander Schleicher Ka 4 Rhönlerche II während eines Schulflugs nahe Pilatussüdfuss, Schweiz, mit einem Telefonkabel. Das Segelflugzeug, gesteuert von einem Flugschüler, traf das Kabel einer Seilbahn und stürzte ab, was zur Zerstörung des Flugzeugs und dem Tod des Piloten führte. Der Vorfall ereignete sich, als das Segelflugzeug nahe am Berg in einer Zone mit Hindernissen flog. Die Wetterbedingungen waren allgemein günstig, jedoch mit schwachen Aufwinden.

1. Aerotow to ridge: The student pilot launched by aerotow from Kägiswil and was towed to about 900 m above ground over the hindrance-free western part of the Pilatus south slope near Schwändi-Längenmatt.
2. Weak ridge lift: In the Pilatus south-slope area the available updrafts were weak and marginal, encouraging flight close to the terrain to maintain height.
3. Flight into cable zone: After initially soaring in a safer area and following another glider, the student left that area and began ridge-soaring back and forth along the slope beneath Chretzenalp in the vicinity of the Aeschi–Chretzenalp cableway.
4. Low, close ridge run: While performing hang-soaring passes in weak lift at low height and close to the mountainside, the student flew into a zone containing multiple cableway wires.
5. Telephone cable not seen: Although the pilot likely recognized the main support and haul cables, he failed to perceive the thinner, slightly higher telephone cable of the cableway.
6. Collision with cable: The right wing leading edge struck the 6 mm telephone cable of the Aeschi–Chretzenalp cableway, tearing away about 3.2 m of the wing’s nose skin and causing a sudden loss of speed and control.
7. Crash - fatal: Following the cable strike and severe wing damage, the glider rolled toward the slope and dived steeply into the Giessbach couloir, impacting rocks and fatally injuring the pilot while destroying the aircraft.